Adaptor for joining towing bar to nose wheel of aircraft

ABSTRACT

Towing bars for joining towing vehicles to the front wheel axles of aircraft often include a pair of parallel bars having cylindrical bosses connected to the trailing ends of the bars and opposing one another. The bosses are intended to fit into sockets or bores in the opposing ends of the axle. With certain airplanes the bosses may not be long enough to clear the opposed sides of a nose wheel tire sufficiently so that their ends project into the axle openings. An adaptor to allow such towing bars to fit these aircraft includes a cylindrical rod of a diameter adapted to extend into the end bore of the axle joined at its opposite end to a coaxial, larger diameter cylindrical hub having a bore adapted to receive one of the tow bar bosses. The length of the adaptor hub is such that the tow bar arms clear the outer sides of the tire when the cylindrical rod ends are within the axle bores, allowing the nose wheel to freely rotate during towing and prevent damage to the tire.

FIELD OF THE INVENTION

This invention relates to adaptors for use with tow bars for aircraft,of the type having a pair of parallel arms carrying opposed bosses attheir outer ends adapted to fit within bores formed in the outer ends ofthe nose wheel axle.

BACKGROUND OF THE INVENTION

Airplanes are often towed on the ground using elongated tow bars whichengage the plane's nose wheel.

Most tow bars have a forward end adapted to be connected to a towingvehicle such as a truck or the like, usually through a hitch, and therear end of the bar terminates with a cross bar extending transverselyto the length of the tow bar in both directions with a pair of rearwardextending arms affixed to each outer end of the cross bar. The opposingsections of the trailing ends of each of these arms carry cylindricalbosses which project in opposition to one another and are adapted toextend into the bores formed in the axle end on each side of the nosewheel.

The trailing arms must be separated sufficiently to clear the nose wheeltire supported on the axle. However, since neither the nose wheelconfigurations used by different aircraft manufacturers or the tireswhich may be used on a given nose wheel axle are standard, many of thetrailing arms on the tow bar cannot be sufficiently separated to clear atire supported on the nose wheel axle, to avoid damage to the tireduring towing, and still allow the axle-engaging bosses fixed to therear ends of the arms to project inwardly far enough to engage the boreson opposite ends of the axle.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides elongated adaptors havingbores or sockets at one end of a proper configuration to receive one ofthe inwardly extending tow bar bosses and terminating at the other endin a cylindrical rod adapted to fit into an axle bore. The length of theadaptor is greater than the distance from the outer surface of the nosewheel tire to the adjacent outer end of the wheel axle so that therearwardly extending arm that supports the boss clears the outside ofthe tire and does not interfere with rotation of the tire while thevehicle is being towed.

In a preferred embodiment of the invention the adaptor takes the form ofa cylindrical rod having a diameter complementary to the axle bore andhaving its outer end, opposite to the end of the rod that engages theaxle, integral with a coaxial cylindrical hub of greater diameter. Theouter end of the hub is formed with a central bore or socket adapted toreceive the boss formed on the end of the towing bar arm. The length ofthe adaptor, from the end that extends into the axle bore to theopposite end which receives the towing bar boss, exceeds the distancefrom the axle end to the outer projection of the nose wheel tire so thatthe rear arm on the towing bar clears the outside of the tire, allowingthe tire to freely rotate while the vehicle is being towed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and applications of the present inventionwill be made apparent by the following detailed description which makesreference to the accompanying drawings in which:

FIG. 1 is a perspective view illustrating a tow bar connecting the nosewheel of a personal aircraft to a towing hitch mounted on a truck;

FIG. 2 is a detailed view of the nose wheel and the engagement of therear end of the tow bar with recesses formed in the nose wheel axleusing an adaptor of the type illustrated in FIG. 4;

FIG. 3 is a cross-sectional view, partial broken away, of the nose wheeltire and axle end connected to the trailing end of one rearwardprojecting arm of the tow bar using an adaptor of the type illustratedin FIG. 4; and

FIG. 4 is a perspective view of an adaptor for connecting a tow bar tothe nose wheel axis when connection without the adaptor would interferewith the nose wheel tire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a typical form of tow bar for aircraft is generallyindicated at 10. In FIG. 1, the tow bar acts to connect the nose wheelof an aircraft, generally indicated at 12, with some towing means suchas the illustrated hitch 14 connected to a truck 16.

The tow bar employs an elongated member 18 which may be tubular and mayhave a pair of rear wheels 20 which support the bar above the groundalong with a forward wheel 22. The rear end of the bar 10 terminates ina cross member 24 extending laterally to the length of the bar 18 inopposed directions, and has a pair of rearwardly extending arms 26 and28 supported on its opposed ends.

The bar 26 may be connected to the cross member 24 by a hingedconnection 30, to allow the arm 26 to swivel toward and away from theaxle 30 of the nose wheel 12. Each of the rear ends of the bars 26 and28 carry opposed cylindrical bosses 32, only one of which is shown inFIG. 1, which are adapted to engage cylindrical bores 34 in the opposedends of the axle. In alternative types of tow bars, rather thanproviding a hinged connection, one of the bosses may be slidinglysupported in its arm 26 with a spring biasing it toward its extendedposition so that it may be withdrawn against the spring bias to connectthe arm to the axle end.

The tire 38 of the nose wheel may, in certain situations, extend axiallysufficiently outwardly along the axle axis to prevent the boss at theend of the arm from engaging the bore 32 in the wheel axle, because thatwould require a position that interferes with the tire. Accordingly, thepresent invention constitutes an adaptor, generally indicated at 40,consisting of a rod 42, preferably cylindrical and having an outerdiameter that allows it to fit within the bore 32 at the end of an axle.The rod 42 is connected to a coaxial, larger diameter cylindrical hub 44that has a bore or socket 46 at its other end which is complementary tothe bosses 32 which project inwardly from the arms 26 and 28 of the towbar.

The end of the cylindrical hub 44 containing a bore 46 will surround thebosses at the end of the arms 26 and 28 so that the end surface of thehub 40 is flush with the interior surfaces of the arms 26 or 28. In thesituation in which the axial clearance from the axle outer surface 34 tothe axially outer limit of the tire 38 is L, as illustrated in FIG. 3,the axial length of the cylindrical hub 40 plus the length of the rod 42which projects out of the axle bore 32 when the rod is inserted in thebore must be equal to L+X where X is a sufficient length to allow thecylindrical rod 42 to project within the bore at the axle opening.

The adaptor 40 is easy to employ and various adaptors may be created fordifferent aircraft wheels and tow bars.

1. Adaptors for use in connecting aircraft tow bars having a pair ofopposing projecting bosses adapted to extend into complementary socketsformed within each end of an aircraft nose wheel axle, the axlesupporting a wheel carrying a tire that extends by distances L in anaxial direction beyond each end of the axle, each said adaptorcomprising: a cylindrical rod having an end configuration complementaryto the socket and having a coaxial cylindrical hub of greater diameterthan the rod integral with one of the rod ends, the hub having a centralsocket of configuration complementary to the tow bar foamed in its endremote from the end integral with the rod, and the axial length of thehub and the portion of the rod which extends out of the axle socket whenthe end of the rod is engaged in the axle socket exceeding L; whereby,the rods of a pair of adaptors may be inserted into the bores in theopposite ends of the axle and the bosses of the tow bar may be insertedinto hub bores with the tow bar clearing the tire, allowing the nosewheel to freely rotate during towing and prevent damage to the tire. 2.The adaptors of claim 1, wherein the intersection between saidcylindrical rod and said coaxial cylindrical hub constitutes a shoulderextending normally to the axis of the rod and hub.
 3. The adaptors ofclaim 1, wherein adaptors engage each of the opposing projectingcylindrical bosses of the aircraft tow bars.
 4. An adaptor for use inconnecting elongated aircraft tow bars having a connector adapted tojoin a towing vehicle at its forward end and a bar extendingtransversely to the elongated section at the rear end and carrying apair of arms equally spaced from the elongate section of the tow bar andprojecting rearwardly parallel to the elongate section, each armcarrying a projecting cylindrical boss of diameter D₁ on its side facingthe elongated axis of the tow bar, the bosses adapted to extend intocomplementary diametered central bores within each end of an aircraftnose wheel axis, and the axle supporting a wheel carrying a tire thatextends by distances L in an axial direction beyond each end of theaxle, said adaptors comprising: a cylindrical rod having a diameter Dand having a coaxial cylindrical hub of a diameter greater than Dintegral with one of the rod ends, the hub having a central bore of adiameter complementary to the tow bar hub diameter D formed in its endremote from the end integral with the rod, and the axial length of thehub exceeding L; whereby the rods of a pair of such adaptors may beinserted into the bores in the opposite end of the axle and the bossesof the tow bar may be inserted into the hub bores so that the arms ofthe tow bar clear the outer sides of said tire.
 5. Adaptors for use inconnecting aircraft tow bars having a pair of opposing projectingcylindrical bosses of diameter D₁ adapted to extend into complementarydiametered central bores within each end of an aircraft nose wheel axle,the axle supporting a wheel carrying a tire that extends by distances L₁in an axial direction beyond each end of the axle, each said adaptorcomprising: a cylindrical rod having a diameter L₁ having a coaxialcylindrical hub of diameter greater than D₁ integral with one of the rodends, the hub having a central bore of a diameter complementary to thetow bar hub diameter D₁ formed in its end remote from the end integralwith the rod, and the axial length of the hub exceeding L₁; whereby, therods of a pair of adaptors may be inserted into the bores in theopposite ends of the axle and the bosses of the tow bar may be insertedinto hub bores with the tow bar clearing the tire.